<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .float{
            width: 200px;
            height: 200px;
            float: left;
            border: 1px solid black;
            background-color: lightgreen;
        }

    </style>
</head>
<body>
    <div class="float"></div>
    <div style="overflow: hidden;width:100%;height:300px;background-color: lightcyan;">HELLO</div>
    
</body>
</html>